1. Field of The Invention
The present invention relates generally to contained, environmentally controlled, appliances such as refrigerators and freezers. The present invention relates more specifically to a device for providing an audible and visual alarm when an emergency condition exists within a container appliance, a distinctive audible and visual alarm when the appliance door is ajar for more than a certain period of time, and a distinctive audible and visual alarm when the interior temperature of the appliance deviates from a preselected range.
2. Description of the Related Art
There are generally three critical problems that can occur with large stationary container appliances such as refrigerators and freezers that immediately demand the attention of a person in a position to rectify the problems. The first of these situations occurs when a door to the appliance has been left ajar for a period of time sufficient to affect the stability of the environment within the appliance and the integrity of whatever is being kept within the appliance. A second condition occurs when an individual, either because of the typical latching features of such appliance doors, or because the appliance door becomes blocked from the outside, or because the individual inside is otherwise unable to open the appliance door, becomes trapped within the appliance and runs the risk of prolonged exposure to low temperatures or suffocation due to their inability to exit. The third important condition of concern is an excess deviation of the internal temperature of the appliance from a specified temperature range.
In any of the above referenced situations, it is imperative that someone capable of rectifying the situation is alerted to the condition in time to prevent damage to the appliance and or its contents or to extricate the individual who might have become trapped. While access to large cooling appliances such as freezers and refrigerators is necessary for their efficient use, the maintenance of this access way between the inside and outside of the appliance for anything longer than a very short period of time can greatly increase the expense of operating the appliance.
Likewise, in an effort to adequately seal the apertures through which access is maintained, such appliances are normally manufactured with very tight fitting doors and latch mechanisms that are sometimes operable only from the outside of the appliance. It is also possible that an individual working within the freezer or refrigerator might become injured in a manner that would prevent him from being able to open the door even if it were structured to be opened from the inside. Becoming trapped within the appliance, therefore, creates the immediate concern of exposure or suffocation for the trapped occupant. Unless attention can be called to the situation and someone on the outside of the appliance can open the door, serious injury or death could result.
It is well known in the field to provide an alarm system for indicating when a door to such an appliance has been left open for more than a preselected period of time. The mechanisms for triggering the alarm range from simple time delay circuitry that is initiated when the door is opened and remains opened for a period of time, to separate and isolated thermal devices that sense the temperature within the appliance and trigger an alarm when the temperature increases above some preselected value. Depending upon the requirements of the contents of the appliance and the exchange of heat that results from the opening of the door, the time delay could be anywhere from a few seconds to more than a few minutes. The alarm associated with indicating that the door is ajar is typically a light indicator that turns on steadily or flashes so as to attract attention. It is also known to use audible alarms to indicate that the appliance door is ajar.
For very large refrigerators and freezers such as those used in cold storage warehouses and in grocery store coolers, it is often necessary to enter and exit the appliance for the purpose of storing or removing products from its interior. This process normally requires that one or more individuals enter the appliance and, at times, close the door behind them. While some newer walk-in freezers and refrigerators are constructed with latching mechanisms that can be opened from the interior, a good number of older and even some new freezer and refrigerator units do not anticipate the possibility of an individual being trapped inside. It is, therefore, desirable to have some means whereby an individual who does become trapped inside is capable of notifying those on the outside that they are in need of assistance. Even with the possibility that a door latch could be opened from the inside, the failure of such a latch to open as it is structured to do, would have consequences much more severe than usual because of the conditions within the freezer/refrigerator. The above described situation the occupant is unable to operate the appliance door due to a fall or other injury or because the door is blocked from the outside, also creates a condition with severe consequences.
It is, therefore, desirable, even with an appliance door that may normally be opened from the inside to have a means whereby an occupant of the freezer or refrigerator can signal the outside if the door latch means fails or for some other reason they are unable to open the appliance door.
Finally, it is important to have a means for alerting operators of large or small refrigerator/freezer appliances of abnormal and/or out of range temperature conditions within the appliance. These abnormal temperature conditions could be associated with a door ajar condition or may be associated with the failure of some element of the cooling system for the appliance.
These situations, therefore, are the most common and the most serious conditions for which an alarm or other indicator means is appropriate during the operation of a freezer/refrigerator unit. While alarms of either the audio type or visual type are known for each of these situations, the devices previously described suffer from a number of limitations. Very often, the alarm systems are so complex and expensive to implement that they require significant initial costs for installation or significant maintenance costs or both. It is also typical to have to install separate alarm systems for each of the indicated situations that often results in increased costs and some duplication of effort.
It would be advantageous, therefore, to have a single alarm system for refrigerator and freezer appliances that incorporates a system for notifying the operators of the appliance when the door to the appliance is ajar or open for an extended period of time, when there exists a situation within the appliance that requires immediate attention or assistance, and when the temperature within the appliance is critically abnormal.